Virsh interface2

I have provided some patches for virsh iface-list command. This patchset caontains 4 files. 
1> virsh_iface_list.py - The main runner script file which tests virsh iface-list commnd
2> virsh_iface_list.cfg - The configuration file for the same
3> iface.py - It contain certain functions which can be used by virsh_iface_list file, later it can be use other virsh iface commands . In the last pull request it was told that, new function library files would not entertained unless it is very much essential. We will see as the review goes by we will try to reduce the dependency from iface.py

4> virsh.py- three new command definitions are entered. 1> net-info 2> virsh iface-list 3> virsh iface-dumpxml

How it works
1> It tests virsh iface-list command
2> The configuration options are available are all_option="--all",inactive_option="--inactive",no_option
3> It would take all the interfaces available in the host, then rule out some unfit interfaces. let me go in details
all the interfaces in host would found from ifconfig command. The unfit interfaces which can not be considered for iface testing are
3.1> bridged interfaces which are running under some bridge which included virtual interfaces of VMs(vnet1,vnet2) too
3.2> KVM virtual networks virbr0 etc.
                                                                                                                                       
4> It would check one by one interfaces which are filtered from above point 3 and check if the network scripts are available, if yes virsh iface-list should show or else should not. And verify the mac address and state of the interface

I will try to give more info as the review goes by